partial_cmp().unwrap() in the top-k / top-p sort and softmax paths would
panic the engine thread on a single NaN logit. The greedy argmax path
is already NaN-safe. Add a one-pass NaN → -inf sweep on the extracted
last_row before temperature scaling, which is equivalent to masking the
token and keeps the sampler deterministic. Warn once when triggered so
the underlying numeric bug isn't silently hidden.
Gahow Wang
ce10e4a998